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tgseclib/phpseclib/Crypt/TripleDES.php

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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Pure-PHP implementation of Triple DES.
*
* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
*
* PHP versions 4 and 5
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include('Crypt/TripleDES.php');
*
* $des = new Crypt_TripleDES();
*
* $des->setKey('abcdefghijklmnopqrstuvwx');
*
* $size = 10 * 1024;
* $plaintext = '';
* for ($i = 0; $i < $size; $i++) {
* $plaintext.= 'a';
* }
*
* echo $des->decrypt($des->encrypt($plaintext));
* ?>
* </code>
*
* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @category Crypt
* @package Crypt_TripleDES
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVII Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @version $Id: TripleDES.php,v 1.13 2010/02/26 03:40:25 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**
* Include Crypt_DES
*/
if (!class_exists('Crypt_DES')) {
require_once('DES.php');
}
/**
* Encrypt / decrypt using inner chaining
*
* Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (CRYPT_DES_MODE_CBC3).
*/
define('CRYPT_DES_MODE_3CBC', -2);
/**
* Encrypt / decrypt using outer chaining
*
* Outer chaining is used by SSH-2 and when the mode is set to CRYPT_DES_MODE_CBC.
*/
define('CRYPT_DES_MODE_CBC3', CRYPT_DES_MODE_CBC);
/**
* Pure-PHP implementation of Triple DES.
*
* @author Jim Wigginton <terrafrost@php.net>
* @version 0.1.0
* @access public
* @package Crypt_TerraDES
*/
class Crypt_TripleDES {
/**
* The Three Keys
*
* @see Crypt_TripleDES::setKey()
* @var String
* @access private
*/
var $key = "\0\0\0\0\0\0\0\0";
/**
* The Encryption Mode
*
* @see Crypt_TripleDES::Crypt_TripleDES()
* @var Integer
* @access private
*/
var $mode = CRYPT_DES_MODE_CBC;
/**
* Continuous Buffer status
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var Boolean
* @access private
*/
var $continuousBuffer = false;
/**
* Padding status
*
* @see Crypt_TripleDES::enablePadding()
* @var Boolean
* @access private
*/
var $padding = true;
/**
* The Initialization Vector
*
* @see Crypt_TripleDES::setIV()
* @var String
* @access private
*/
var $iv = "\0\0\0\0\0\0\0\0";
/**
* A "sliding" Initialization Vector
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var String
* @access private
*/
var $encryptIV = "\0\0\0\0\0\0\0\0";
/**
* A "sliding" Initialization Vector
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var String
* @access private
*/
var $decryptIV = "\0\0\0\0\0\0\0\0";
/**
* The Crypt_DES objects
*
* @var Array
* @access private
*/
var $des;
/**
* mcrypt resource for encryption
*
* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
*
* @see Crypt_TripleDES::encrypt()
* @var String
* @access private
*/
var $enmcrypt;
/**
* mcrypt resource for decryption
*
* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
*
* @see Crypt_TripleDES::decrypt()
* @var String
* @access private
*/
var $demcrypt;
/**
* Does the enmcrypt resource need to be (re)initialized?
*
* @see Crypt_TripleDES::setKey()
* @see Crypt_TripleDES::setIV()
* @var Boolean
* @access private
*/
var $enchanged = true;
/**
* Does the demcrypt resource need to be (re)initialized?
*
* @see Crypt_TripleDES::setKey()
* @see Crypt_TripleDES::setIV()
* @var Boolean
* @access private
*/
var $dechanged = true;
/**
* Is the mode one that is paddable?
*
* @see Crypt_TripleDES::Crypt_TripleDES()
* @var Boolean
* @access private
*/
var $paddable = false;
/**
* Encryption buffer for CTR, OFB and CFB modes
*
* @see Crypt_TripleDES::encrypt()
* @var Array
* @access private
*/
var $enbuffer = array('encrypted' => '', 'xor' => '', 'pos' => 0, 'enmcrypt_init' => true);
/**
* Decryption buffer for CTR, OFB and CFB modes
*
* @see Crypt_TripleDES::decrypt()
* @var Array
* @access private
*/
var $debuffer = array('ciphertext' => '', 'xor' => '', 'pos' => 0, 'demcrypt_init' => true);
/**
* mcrypt resource for CFB mode
*
* @see Crypt_TripleDES::encrypt()
* @see Crypt_TripleDES::decrypt()
* @var String
* @access private
*/
var $ecb;
/**
* Default Constructor.
*
* Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
* CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used.
*
* @param optional Integer $mode
* @return Crypt_TripleDES
* @access public
*/
function Crypt_TripleDES($mode = CRYPT_DES_MODE_CBC)
{
if ( !defined('CRYPT_DES_MODE') ) {
switch (true) {
case extension_loaded('mcrypt') && in_array('tripledes', mcrypt_list_algorithms()):
define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT);
break;
default:
define('CRYPT_DES_MODE', CRYPT_DES_MODE_INTERNAL);
}
}
if ( $mode == CRYPT_DES_MODE_3CBC ) {
$this->mode = CRYPT_DES_MODE_3CBC;
$this->des = array(
new Crypt_DES(CRYPT_DES_MODE_CBC),
new Crypt_DES(CRYPT_DES_MODE_CBC),
new Crypt_DES(CRYPT_DES_MODE_CBC)
);
$this->paddable = true;
// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
$this->des[0]->disablePadding();
$this->des[1]->disablePadding();
$this->des[2]->disablePadding();
return;
}
switch ( CRYPT_DES_MODE ) {
case CRYPT_DES_MODE_MCRYPT:
switch ($mode) {
case CRYPT_DES_MODE_ECB:
$this->paddable = true;
$this->mode = MCRYPT_MODE_ECB;
break;
case CRYPT_DES_MODE_CTR:
$this->mode = 'ctr';
break;
case CRYPT_DES_MODE_CFB:
$this->mode = 'ncfb';
$this->ecb = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_ECB, '');
break;
case CRYPT_DES_MODE_OFB:
$this->mode = MCRYPT_MODE_NOFB;
break;
case CRYPT_DES_MODE_CBC:
default:
$this->paddable = true;
$this->mode = MCRYPT_MODE_CBC;
}
$this->enmcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
$this->demcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
break;
default:
$this->des = array(
new Crypt_DES(CRYPT_DES_MODE_ECB),
new Crypt_DES(CRYPT_DES_MODE_ECB),
new Crypt_DES(CRYPT_DES_MODE_ECB)
);
// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
$this->des[0]->disablePadding();
$this->des[1]->disablePadding();
$this->des[2]->disablePadding();
switch ($mode) {
case CRYPT_DES_MODE_ECB:
case CRYPT_DES_MODE_CBC:
$this->paddable = true;
$this->mode = $mode;
break;
case CRYPT_DES_MODE_CTR:
case CRYPT_DES_MODE_CFB:
case CRYPT_DES_MODE_OFB:
$this->mode = $mode;
break;
default:
$this->paddable = true;
$this->mode = CRYPT_DES_MODE_CBC;
}
}
}
/**
* Sets the key.
*
* Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or
* 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate.
*
* DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
*
* If the key is not explicitly set, it'll be assumed to be all zero's.
*
* @access public
* @param String $key
*/
function setKey($key)
{
$length = strlen($key);
if ($length > 8) {
$key = str_pad($key, 24, chr(0));
// if $key is between 64 and 128-bits, use the first 64-bits as the last, per this:
// http://php.net/function.mcrypt-encrypt#47973
//$key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24);
} else {
$key = str_pad($key, 8, chr(0));
}
$this->key = $key;
switch (true) {
case CRYPT_DES_MODE == CRYPT_DES_MODE_INTERNAL:
case $this->mode == CRYPT_DES_MODE_3CBC:
$this->des[0]->setKey(substr($key, 0, 8));
$this->des[1]->setKey(substr($key, 8, 8));
$this->des[2]->setKey(substr($key, 16, 8));
}
$this->enchanged = $this->dechanged = true;
}
/**
* Sets the password.
*
* Depending on what $method is set to, setPassword()'s (optional) parameters are as follows:
* {@link http://en.wikipedia.org/wiki/PBKDF2 pbkdf2}:
* $hash, $salt, $method
*
* @param String $password
* @param optional String $method
* @access public
*/
function setPassword($password, $method = 'pbkdf2')
{
$key = '';
switch ($method) {
default: // 'pbkdf2'
list(, , $hash, $salt, $count) = func_get_args();
if (!isset($hash)) {
$hash = 'sha1';
}
// WPA and WPA2 use the SSID as the salt
if (!isset($salt)) {
$salt = 'phpseclib';
}
// RFC2898#section-4.2 uses 1,000 iterations by default
// WPA and WPA2 use 4,096.
if (!isset($count)) {
$count = 1000;
}
if (!class_exists('Crypt_Hash')) {
require_once('Crypt/Hash.php');
}
$i = 1;
while (strlen($key) < 24) { // $dkLen == 24
$hmac = new Crypt_Hash();
$hmac->setHash($hash);
$hmac->setKey($password);
$f = $u = $hmac->hash($salt . pack('N', $i++));
for ($j = 2; $j <= $count; $j++) {
$u = $hmac->hash($u);
$f^= $u;
}
$key.= $f;
}
}
$this->setKey($key);
}
/**
* Sets the initialization vector. (optional)
*
* SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explictly set, it'll be assumed
* to be all zero's.
*
* @access public
* @param String $iv
*/
function setIV($iv)
{
$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, 8), 8, chr(0));
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->setIV($iv);
$this->des[1]->setIV($iv);
$this->des[2]->setIV($iv);
}
$this->enchanged = $this->dechanged = true;
}
/**
* Generate CTR XOR encryption key
*
* Encrypt the output of this and XOR it against the ciphertext / plaintext to get the
* plaintext / ciphertext in CTR mode.
*
* @see Crypt_TripleDES::decrypt()
* @see Crypt_TripleDES::encrypt()
* @access private
* @param String $iv
*/
function _generate_xor(&$iv)
{
$xor = $iv;
for ($j = 4; $j <= 8; $j+=4) {
$temp = substr($iv, -$j, 4);
switch ($temp) {
case "\xFF\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4);
break;
case "\x7F\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4);
break 2;
default:
extract(unpack('Ncount', $temp));
$iv = substr_replace($iv, pack('N', $count + 1), -$j, 4);
break 2;
}
}
return $xor;
}
/**
* Encrypts a message.
*
* @access public
* @param String $plaintext
*/
function encrypt($plaintext)
{
if ($this->paddable) {
$plaintext = $this->_pad($plaintext);
}
// if the key is smaller then 8, do what we'd normally do
if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
$ciphertext = $this->des[2]->encrypt($this->des[1]->decrypt($this->des[0]->encrypt($plaintext)));
return $ciphertext;
}
if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
if ($this->enchanged) {
mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
if ($this->mode == 'ncfb') {
mcrypt_generic_init($this->ecb, $this->key, "\0\0\0\0\0\0\0\0");
}
$this->enchanged = false;
}
if ($this->mode != 'ncfb' || !$this->continuousBuffer) {
$ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
} else {
$iv = &$this->encryptIV;
$pos = &$this->enbuffer['pos'];
$len = strlen($plaintext);
$ciphertext = '';
$i = 0;
if ($pos) {
$orig_pos = $pos;
$max = 8 - $pos;
if ($len >= $max) {
$i = $max;
$len-= $max;
$pos = 0;
} else {
$i = $len;
$pos+= $len;
$len = 0;
}
$ciphertext = substr($iv, $orig_pos) ^ $plaintext;
$iv = substr_replace($iv, $ciphertext, $orig_pos, $i);
$this->enbuffer['enmcrypt_init'] = true;
}
if ($len >= 8) {
if ($this->enbuffer['enmcrypt_init'] === false || $len > 950) {
if ($this->enbuffer['enmcrypt_init'] === true) {
mcrypt_generic_init($this->enmcrypt, $this->key, $iv);
$this->enbuffer['enmcrypt_init'] = false;
}
$ciphertext.= mcrypt_generic($this->enmcrypt, substr($plaintext, $i, $len - $len % 8));
$iv = substr($ciphertext, -8);
$i = strlen($ciphertext);
$len%= 8;
} else {
while ($len >= 8) {
$iv = mcrypt_generic($this->ecb, $iv) ^ substr($plaintext, $i, 8);
$ciphertext.= $iv;
$len-= 8;
$i+= 8;
}
}
}
if ($len) {
$iv = mcrypt_generic($this->ecb, $iv);
$block = $iv ^ substr($plaintext, $i);
$iv = substr_replace($iv, $block, 0, $len);
$ciphertext.= $block;
$pos = $len;
}
return $ciphertext;
}
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
}
return $ciphertext;
}
if (strlen($this->key) <= 8) {
$this->des[0]->mode = $this->mode;
return $this->des[0]->encrypt($plaintext);
}
$des = $this->des;
$buffer = &$this->enbuffer;
$continuousBuffer = $this->continuousBuffer;
$ciphertext = '';
switch ($this->mode) {
case CRYPT_DES_MODE_ECB:
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
// all of these _processBlock calls could, in theory, be put in a function - say Crypt_TripleDES::_ede_encrypt() or something.
// only problem with that: it would slow encryption and decryption down. $this->des would have to be called every time that
// function is called, instead of once for the whole string of text that's being encrypted, which would, in turn, make
// encryption and decryption take more time, per this:
//
// http://blog.libssh2.org/index.php?/archives/21-Compiled-Variables.html
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
$ciphertext.= $block;
}
break;
case CRYPT_DES_MODE_CBC:
$xor = $this->encryptIV;
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8) ^ $xor;
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
$xor = $block;
$ciphertext.= $block;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
}
break;
case CRYPT_DES_MODE_CTR:
$xor = $this->encryptIV;
if (strlen($buffer['encrypted'])) {
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
if (strlen($block) > strlen($buffer['encrypted'])) {
$key = $this->_generate_xor($xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$buffer['encrypted'].= $key;
}
$key = $this->_string_shift($buffer['encrypted'], 8);
$ciphertext.= $block ^ $key;
}
} else {
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
$key = $this->_generate_xor($xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$ciphertext.= $block ^ $key;
}
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
if ($start = strlen($plaintext) & 7) {
$buffer['encrypted'] = substr($key, $start) . $buffer['encrypted'];
}
}
break;
case CRYPT_DES_MODE_CFB:
if (strlen($buffer['xor'])) {
$ciphertext = $plaintext ^ $buffer['xor'];
$iv = $buffer['encrypted'] . $ciphertext;
$start = strlen($ciphertext);
$buffer['encrypted'].= $ciphertext;
$buffer['xor'] = substr($buffer['xor'], strlen($ciphertext));
} else {
$ciphertext = '';
$iv = $this->encryptIV;
$start = 0;
}
for ($i = $start; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
$iv = $des[0]->_processBlock($iv, CRYPT_DES_ENCRYPT);
$iv = $des[1]->_processBlock($iv, CRYPT_DES_DECRYPT);
$xor= $des[2]->_processBlock($iv, CRYPT_DES_ENCRYPT);
$iv = $block ^ $xor;
if ($continuousBuffer && strlen($iv) != 8) {
$buffer = array(
'encrypted' => $iv,
'xor' => substr($xor, strlen($iv))
);
}
$ciphertext.= $iv;
}
if ($this->continuousBuffer) {
$this->encryptIV = $iv;
}
break;
case CRYPT_DES_MODE_OFB:
$xor = $this->encryptIV;
if (strlen($buffer['xor'])) {
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
if (strlen($block) > strlen($buffer['xor'])) {
$xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$buffer['xor'].= $xor;
}
$key = $this->_string_shift($buffer['xor'], 8);
$ciphertext.= $block ^ $key;
}
} else {
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$ciphertext.= substr($plaintext, $i, 8) ^ $xor;
}
$key = $xor;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
if ($start = strlen($plaintext) & 7) {
$buffer['xor'] = substr($key, $start) . $buffer['xor'];
}
}
}
return $ciphertext;
}
/**
* Decrypts a message.
*
* @access public
* @param String $ciphertext
*/
function decrypt($ciphertext)
{
if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
$plaintext = $this->des[0]->decrypt($this->des[1]->encrypt($this->des[2]->decrypt($ciphertext)));
return $this->_unpad($plaintext);
}
if ($this->paddable) {
// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
$ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, chr(0));
}
if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
if ($this->dechanged) {
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
if ($this->mode == 'ncfb') {
mcrypt_generic_init($this->ecb, $this->key, "\0\0\0\0\0\0\0\0");
}
$this->dechanged = false;
}
if ($this->mode != 'ncfb' || !$this->continuousBuffer) {
$plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
} else {
$iv = &$this->decryptIV;
$pos = &$this->debuffer['pos'];
$len = strlen($ciphertext);
$plaintext = '';
$i = 0;
if ($pos) {
$orig_pos = $pos;
$max = 8 - $pos;
if ($len >= $max) {
$i = $max;
$len-= $max;
$pos = 0;
} else {
$i = $len;
$pos+= $len;
$len = 0;
}
$plaintext = substr($iv, $orig_pos) ^ $ciphertext;
$iv = substr_replace($iv, substr($ciphertext, 0, $i), $orig_pos, $i);
}
if ($len >= 8) {
$cb = substr($ciphertext, $i, $len - $len % 8);
$plaintext.= mcrypt_generic($this->ecb, $iv . $cb) ^ $cb;
$iv = substr($cb, -8);
$len%= 8;
}
if ($len) {
$iv = mcrypt_generic($this->ecb, $iv);
$cb = substr($ciphertext, -$len);
$plaintext.= $iv ^ $cb;
$iv = substr_replace($iv, $cb, 0, $len);
$pos = $len;
}
return $plaintext;
}
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
}
return $this->paddable ? $this->_unpad($plaintext) : $plaintext;
}
if (strlen($this->key) <= 8) {
$this->des[0]->mode = $this->mode;
$plaintext = $this->des[0]->decrypt($ciphertext);
return $this->paddable ? $this->_unpad($plaintext) : $plaintext;
}
$des = $this->des;
$buffer = &$this->debuffer;
$continuousBuffer = $this->continuousBuffer;
$plaintext = '';
switch ($this->mode) {
case CRYPT_DES_MODE_ECB:
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
$plaintext.= $block;
}
break;
case CRYPT_DES_MODE_CBC:
$xor = $this->decryptIV;
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$orig = $block = substr($ciphertext, $i, 8);
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
$plaintext.= $block ^ $xor;
$xor = $orig;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
}
break;
case CRYPT_DES_MODE_CTR:
$xor = $this->decryptIV;
if (strlen($buffer['ciphertext'])) {
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
if (strlen($block) > strlen($buffer['ciphertext'])) {
$key = $this->_generate_xor($xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$buffer['ciphertext'].= $key;
}
$key = $this->_string_shift($buffer['ciphertext'], 8);
$plaintext.= $block ^ $key;
}
} else {
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
$key = $this->_generate_xor($xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$plaintext.= $block ^ $key;
}
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
if ($start = strlen($plaintext) & 7) {
$buffer['ciphertext'] = substr($key, $start) . $buffer['ciphertext'];
}
}
break;
case CRYPT_DES_MODE_CFB:
if (strlen($buffer['ciphertext'])) {
$plaintext = $ciphertext ^ substr($this->decryptIV, strlen($buffer['ciphertext']));
$buffer['ciphertext'].= substr($ciphertext, 0, strlen($plaintext));
if (strlen($buffer['ciphertext']) != 8) {
$block = $this->decryptIV;
} else {
$block = $buffer['ciphertext'];
$xor = $des[0]->_processBlock($buffer['ciphertext'], CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$buffer['ciphertext'] = '';
}
$start = strlen($plaintext);
} else {
$plaintext = '';
$xor = $des[0]->_processBlock($this->decryptIV, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$start = 0;
}
for ($i = $start; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
$plaintext.= $block ^ $xor;
if ($continuousBuffer && strlen($block) != 8) {
$buffer['ciphertext'].= $block;
$block = $xor;
} else if (strlen($block) == 8) {
$xor = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
}
}
if ($this->continuousBuffer) {
$this->decryptIV = $block;
}
break;
case CRYPT_DES_MODE_OFB:
$xor = $this->decryptIV;
if (strlen($buffer['xor'])) {
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
if (strlen($block) > strlen($buffer['xor'])) {
$xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$buffer['xor'].= $xor;
}
$key = $this->_string_shift($buffer['xor'], 8);
$plaintext.= $block ^ $key;
}
} else {
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT);
$xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT);
$plaintext.= substr($ciphertext, $i, 8) ^ $xor;
}
$key = $xor;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
if ($start = strlen($ciphertext) & 7) {
$buffer['xor'] = substr($key, $start) . $buffer['xor'];
}
}
}
return $this->paddable ? $this->_unpad($plaintext) : $plaintext;
}
/**
* Treat consecutive "packets" as if they are a continuous buffer.
*
* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets
* will yield different outputs:
*
* <code>
* echo $des->encrypt(substr($plaintext, 0, 8));
* echo $des->encrypt(substr($plaintext, 8, 8));
* </code>
* <code>
* echo $des->encrypt($plaintext);
* </code>
*
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
* another, as demonstrated with the following:
*
* <code>
* $des->encrypt(substr($plaintext, 0, 8));
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* </code>
* <code>
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* </code>
*
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
*
* Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
* however, they are also less intuitive and more likely to cause you problems.
*
* @see Crypt_TripleDES::disableContinuousBuffer()
* @access public
*/
function enableContinuousBuffer()
{
$this->continuousBuffer = true;
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->enableContinuousBuffer();
$this->des[1]->enableContinuousBuffer();
$this->des[2]->enableContinuousBuffer();
}
}
/**
* Treat consecutive packets as if they are a discontinuous buffer.
*
* The default behavior.
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @access public
*/
function disableContinuousBuffer()
{
$this->continuousBuffer = false;
$this->encryptIV = $this->iv;
$this->decryptIV = $this->iv;
$this->enchanged = true;
$this->dechanged = true;
$this->enbuffer = array('encrypted' => '', 'xor' => '', 'pos' => 0, 'enmcrypt_init' => true);
$this->debuffer = array('ciphertext' => '', 'xor' => '', 'pos' => 0, 'demcrypt_init' => true);
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->disableContinuousBuffer();
$this->des[1]->disableContinuousBuffer();
$this->des[2]->disableContinuousBuffer();
}
}
/**
* Pad "packets".
*
* DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not
* a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight.
*
* Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1,
* where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping
* away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is
* transmitted separately)
*
* @see Crypt_TripleDES::disablePadding()
* @access public
*/
function enablePadding()
{
$this->padding = true;
}
/**
* Do not pad packets.
*
* @see Crypt_TripleDES::enablePadding()
* @access public
*/
function disablePadding()
{
$this->padding = false;
}
/**
* Pads a string
*
* Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8).
* 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7)
*
* If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless
* and padding will, hence forth, be enabled.
*
* @see Crypt_TripleDES::_unpad()
* @access private
*/
function _pad($text)
{
$length = strlen($text);
if (!$this->padding) {
if (($length & 7) == 0) {
return $text;
} else {
user_error("The plaintext's length ($length) is not a multiple of the block size (8)", E_USER_NOTICE);
$this->padding = true;
}
}
$pad = 8 - ($length & 7);
return str_pad($text, $length + $pad, chr($pad));
}
/**
* Unpads a string
*
* If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong
* and false will be returned.
*
* @see Crypt_TripleDES::_pad()
* @access private
*/
function _unpad($text)
{
if (!$this->padding) {
return $text;
}
$length = ord($text[strlen($text) - 1]);
if (!$length || $length > 8) {
return false;
}
return substr($text, 0, -$length);
}
/**
* String Shift
*
* Inspired by array_shift
*
* @param String $string
* @param optional Integer $index
* @return String
* @access private
*/
function _string_shift(&$string, $index = 1)
{
$substr = substr($string, 0, $index);
$string = substr($string, $index);
return $substr;
}
}
// vim: ts=4:sw=4:et:
// vim6: fdl=1:
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